BUNSEKI KAGAKU
Print ISSN : 0525-1931
Volume 45, Issue 4
Displaying 1-12 of 12 articles from this issue
  • Masakazu HORIE, Hiroyuki NAKAZAWA
    1996 Volume 45 Issue 4 Pages 279-308
    Published: April 05, 1996
    Released on J-STAGE: May 29, 2009
    JOURNAL FREE ACCESS
    For the analysis of residual chemicals in food to ensure food safety, many assay techniques have been developed such as gas chromatography (GC), gas chromatography-mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC). This paper deals with the analysis of residual chemicals including (A) pesticides (organochlorine and organophosphorus pesticides), (B) veterinary drugs (antibiotics, synthetic antibacterials, hormones and antiparasitic drugs), (C) food additives (preservatives, fungicides and antioxidants), (D) environmental pollution materials (PCB, dioxins, organotin compounds and volatile chlorinated organic compounds) and (E) natural toxins (mycotoxin). Legal regulations and the safety assessment of these chemicals are also outlined in this paper.
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  • Shinya KITAGAWA, Takao TSUDA, Takatoshi MATSUMOTO
    1996 Volume 45 Issue 4 Pages 309-313
    Published: April 05, 1996
    Released on J-STAGE: January 15, 2010
    JOURNAL FREE ACCESS
    In this paper, we propose a novel pre-concentration method using an electric field. After concentration enhancement in a microsyringe (in a volume of 50 μl or 10 μl), the concentrated solution is injected directly to the liquid chromatography system. Because concentration and injection were done with the same syringe, threr is very little loss of sample solution. For higher concentration enhancement, this microsyringe concentration method has been performed with an electrode transfer, in which a counter electrode is transferred to another electrode during the concentration process, thereby accomplishing the electroconcentration in a very short period, i.e. a few or several minutes. A typical example is described. By using 50 μl microsyringe, an aqueous solution of 8 μM benzoic acid in 2 mM L-Arginine was concentrated with an application of 300 V for a 3 min operational period. The concentration enhancement of 3.5 μl around the electrode was 10.8 times the original solution.
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  • Akira TORIBA, Hiroaki KUBO, Toshio KINOSHITA
    1996 Volume 45 Issue 4 Pages 315-320
    Published: April 05, 1996
    Released on J-STAGE: May 07, 2010
    JOURNAL FREE ACCESS
    A general method has been developed for the selective ultraviolet detection of amino acids using reversed-phase liquid chromatography. The method is based on the formation of copper(II)-amino acid complexes by the reaction of amino acid with copper(II) ions in an alkaline mobile phase through an in-line reactor containing copper metal. Seven amino acids were separated on a column containing C18-bonded vinyl alcohol copolymer gel (Asahipak ODP-50, 5μm, 250 × 6 mm i.d. ) and the alkaline mobile phase containing 10 mM hexadecyltrimethyl ammonium as an ion pair reagent (pH 11.0, 25 mM phosphate buffer). Copper metal (100200 mesh, 150 mg) was packed into the in-line reactor (4 × 4 mm i.d.). The detection was carried out at 255 nm. A detection limit of 800 pg (S/N=3) was obtained for proline.
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  • Kenichi WATANABE, Tomoko MIYAKE, Tadaoki OKUMOTO
    1996 Volume 45 Issue 4 Pages 321-326
    Published: April 05, 1996
    Released on J-STAGE: May 29, 2009
    JOURNAL FREE ACCESS
    A model allophanate compound was prepared by reacting primary and secondary alcohols with excess di-isocyanate at a high temperature. This was then treated with butylamine (BA) and 1-(3-aminopropyl)-1, 1, 3, 3, 3-pentamethyl disiloxane (APDS). The resultant products were analysed by comparing their 13C-NMR spectra with the corresponding urethane compounds. These model compounds possessing uretidione and isocyanurate groups, which had been derived from diphenyl methanediisocyanate, were also treated with the above two amines. The progression of their reactions was determined by means of IR spectroscopy. As a result of the above experiments, it was found that the isocyanurate linkages were destroyed when treated with BA but not when APDS was applied. The other model compounds reacted with both amines. It is anticipated that the presence of isocyanurate linkages in polyurethane networks can be distinguished from allophanate linkages, and their respective volumes determined using the amine decomposition technique outlined above.
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  • Yoshiteru MIZUKOSHI, Kenji OKITSU, Hiroshi BANDOW, Yoshio NAGATA, Yasu ...
    1996 Volume 45 Issue 4 Pages 327-331
    Published: April 05, 1996
    Released on J-STAGE: May 29, 2009
    JOURNAL FREE ACCESS
    An improved colorimetric method for the determination of noble metal ions in a solution containing multiple components, such as ultra fine particles formed by reduction of noble metal ions and surfactants was investigated. Usually, it is difficult to determine concentrations of noble metal ions in such solutions due to the interference of surface plasmon absorption of metal particles. In the present method, the addition of sodium bromide for gold ions and sodium iodide for palladium and platinum ions induced aggregation of noble metal particles, which were easily removed by filtration. Sodium cations may contribute to the precipitation process by salting-out. In addition, coordination of bromide or iodide ions to metal ions via a ligand exchange reaction gave metal complexes having a relatively large absorption coefficient in the visible region, which is suitable for colorimetry. The lower limits of determination were 5.08×10-2 mM for gold, 1.32×10-1 mM for palladium, and 5.82×10-2 mM for platinum. It is possible to measure the reduction rates of noble metal ions under various conditions by this method.
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  • Hirotsugu MINAMI, Norie HIROTOMI, Sadanobu INOUE, Ikuo ATSUYA
    1996 Volume 45 Issue 4 Pages 333-340
    Published: April 05, 1996
    Released on J-STAGE: May 25, 2010
    JOURNAL FREE ACCESS
    A convenient analytical method for the determination of trace amounts of cobalt in geological samples was investigated by atomic absorption spectrometry (AAS) equipped with a pyro-graphite furnace. In order to obtain accurate analytical results, two methods of preparing calibration curves, the standard addition method and the matrix matching method, were examined in detail by using the standard geological samples issued from the Geological Survey of Japan (GSJ ; JA-1, JA-3, JG-3 and JG-1a). The analytical results obtained by AAS were ascertained by using an inductively coupled plasma atomic emission spectrometry (ICP-AES) equipped with an ultrasonic nebulizer and microwave induced nitrogen plasma mass spectrometry (MIP-MS). The proposed method was applied to the determination of cobalt at 1μg/g levels in geological samples which will be certified by the Korea Institute of Energy and Resources (KIER; KG-1 and KG-2). The detection limit (three times of relative standard deviation of blank) for cobalt was 5.3μg/l when 10μl of solution was measured. The precision for the deter-mination (relative standard deviation at 5 determinations) of cobalt was 0.4-3.4% when standard geological samples were analyzed.
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  • Kunihiro WATANABE, Kunihiro OHBA, Masayuki ITAGAKI
    1996 Volume 45 Issue 4 Pages 341-346
    Published: April 05, 1996
    Released on J-STAGE: January 15, 2010
    JOURNAL FREE ACCESS
    Fluorometric determinations of average Cu valence in superconductor Y-Ba-Cu-O were performed by flow injection analysis (FIA). The present FIA apparatus had triple channels for streams of (i) distilled water (carrier), (ii) 5% ascorbic acid solution (pH 2.5) and (iii) 0.25% ο-phenylenediamine solution. A sample solution was prepared by dissolving about 0.02 μg of the Y-Ba-Cu-O in 5 ml of 5% ascorbic acid solution. The sample solution (100μl) containing Cu(II) and/or Cu(III) ions was injected into the carrier (i). Cu(II) and/or Cu(III) ions oxidized ascorbic acid in the stream (ii) to dehydroascorbic acid, which reacted with ο-phenylenediamine in the stream (iii) to produce a kind of quinoxaline derivative. The fluorescence intensity of the quinoxaline derivative (λex= 350 nm, λem=430nm) constituted the parameter for the average Cu valence, 2[Cu(III)]+ [Cu(II)]. On the other hand, the concentration of the total Cu ions, [Cu]total, was determined by atomic absorption spectrometry. The average Cu valence, nav, can be calculated according to the following equation: nav=(2[Cu(III)] + [Cu(II)])/[Cu]total+1. The results agreed well with those obtained by iodometry. In the present method, the lower limit of determination was 0.09 ppb which corresponded to 0.02μg of Y-Ba-Cu-O sample.
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  • Yoshikazu KIKUTA, Yoshihiko MIYASAKA, Tetsuya ASUKE, Hiroaki YAMANASHI ...
    1996 Volume 45 Issue 4 Pages 347-351
    Published: April 05, 1996
    Released on J-STAGE: May 29, 2009
    JOURNAL FREE ACCESS
    Contact mode Atomic Force Microscopy (AFM) was applied to observe surface morphology and to measure surface roughness of several polyolefin films, namely a blend of Linear Low Density Polyethylene and Low Density Polyethylene (LLDPE/LDPE), a blend of High Density Polyethylene and Low Density Polyethylene (HDPE/LDPE), and Cast Polypropylene (CPP). AFM pictures showed no damage on the surface of these films and morphology could be well observed. Roughness parameters were obtained from cross-section profiles of AFM pictures. Rz (mean roughness of ten points) was adopted as the roughness parameter. Rz values of LLDPE/LDPE, HDPE/LDPE and CPP are below 100 nm, 140 nm, and 800 nm, respectively. Rz is compared with surface haze, which is one measure of optical transparency of polymer films. It was found that the Rz values are correlated to the surface haze and that this relation is consistent within these three kinds of polyolefin resins.
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  • Hideyuki ITABASHI, Hisashi YUASA, Hiroshi KAWAMOTO
    1996 Volume 45 Issue 4 Pages 353-356
    Published: April 05, 1996
    Released on J-STAGE: January 15, 2010
    JOURNAL FREE ACCESS
    Based on the Hard and Soft Acids and Bases (HSAB) principle, the possibility of extractive separation of cadmium(II) from zinc(II) with some chelating agents was discussed. The separation factor (S.F. = logDCd-logDZn) for extraction of cadmium(II) from zinc(II) is derived from the HSAB principle as follows: S.F.=(SACd-SAZn)SB +(σACdAZnB where SA, σA, SB and σBrepresent strength factor of a metal ion, soft factor of a metal ion, strength factor of chelating agent and soft factor of chelating agent, respectively. If it is assumed that S.F.≥4 is required for the quantitative separation of cadmium(II) from zinc(II), the above equation leads to the following relationship (where SAZn =32.2, SACd=28.1, σAZn=-26.6, σACd =-12.6): σB≥0.286+0.293SB. This equation suggests that the possibility of the quantitative separation of cadmium(II) from zinc (II) with a suitable chelating agent can be estimated from its SB and σB values. In this paper, some chelating agents such as thenoyltrifluoroacetone (TTA, SB = 0.312, σB=0.101), monothiothenoyltrifluoroacetone (STTA, SB = 0.26, σB-=0.31), diethyldithiocarbamic acid (DDTC, SB=0.569, σB=0.433), dithizone (SB=0.42, σB=0.20) and 8-quinolinol (SB=0.623, σB=0.133) were applied. As a result, it was concluded that DDTC is the most effective chelating agent for the separation of cadmium(II) from zinc(II) although quantitative separation cannot be achieved. However, the use of an ionpair extraction system using a mixture of DDTC and capriquat enables the quantitative separation of cadmium(II) from zinc(II).
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  • Manami TANIMOTO, Hirotaka FUKUMURA
    1996 Volume 45 Issue 4 Pages 357-361
    Published: April 05, 1996
    Released on J-STAGE: May 07, 2010
    JOURNAL FREE ACCESS
    Microwave digestion techniques were examined to determine impurities in silicon nitride and silicon carbide powders. Each sample was decomposed within two hours by the following procedures. A 0.5 g sample of silicon nitride powder and mixture of 9 ml of hydrofluoric acid and 3 ml of nitric acid were put into a Teflon pressure vessel with a polypropylene jacket, and then decomposed by heating in a microwave oven. Similarly an approximately 0.5 g sample of silicon carbide (β-SiC) powder was decomposed with a mixture of 3 ml of hydrofluoric acid, 3 ml of nitric acid and 6 ml of sulfuric acid by heating in a microwave oven. α-SiC powder, however did not dissolve, while β-SiC powder did. The proposed methods were applied to JCRM-R-005 and some commercial powders of silicon nitride and silicon carbide, and the impurities were determined by ICP-AES and AAS. Analytical results were compared with the results of conventional acid pressure decomposition method.
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  • Atsushi YAMAMOTO, Akinobu MATSUNAGA, Akemi YASUI
    1996 Volume 45 Issue 4 Pages 363-366
    Published: April 05, 1996
    Released on J-STAGE: May 29, 2009
    JOURNAL FREE ACCESS
    The nitrate ion selective electrode has been utilized in the determination of nitrate in vegetables. The only pretreatment of the vegetable extracts was to pass them through the anion exchange cartridge prior to nitrate determination using the ion selective electrode (ISE). Nitrate contents in these extracts were also determined by ion chromatography (IC). Both results agreed well in most vegetables except those rich in organic acids or carbohydrates. The ISE method is superior in the time required for an IC determination, so it is especially useful for rapid nitrate determinations in a large number of restricted vegetables.
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  • Yasuhiro HAYAKAWA
    1996 Volume 45 Issue 4 Pages 367-368
    Published: April 05, 1996
    Released on J-STAGE: May 29, 2009
    JOURNAL FREE ACCESS
    The mechanical and metallurgical properties of iron and steel are significantly influenced by the contents and forms of nonmetallic elements. In order to control the chemical composition of steel precisely and rapidly, new analytical methods for nonmetallic elements have been developed. These methods are characterized by the use of a chemical sensor which is capable of detecting the specified gases simply, rapidly and sensitively. An on-line analytical method for hydrogen in molten steel and a method for continuous measurement of hydrogen which can permeate a bolt were developed by using a SnO2 semiconductor gas sensor. A method for simultaneous determination of gas mixtures was also developed using plural semiconductor gas sensors, and was applied to measuring concentrations of coke oven gases. A rapid determination method for phosphorus and sulfur in iron was also developed by using a reflectance photometric sensor with gas detecting tape. These methods are capable of being used at the production sites, and contributing to the precise control of the chemical composition of steel.
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